Picoscope 3224, 100ks/s, 'PicoScope6_r6_7_40' ? ,Capturing 2 channels of RS422 data TX/RX, 1200,o,8,1 . 11 bytes ~106ms each channel 160ms from start of TX to end of TX, Its on a 1s cycle so plenty of idle time between polls.With 20ms/div it triggers reliably on the first rising edge of data, But with 50ms/div it often triggers off other rising edges in the data packet. (20ms/div won't capture full RX packet).

Have tried trigger off either channel, Serial decode enabled/disabled, changing samples/sec., numerous advanced triggers, run laptop on battery(unplugged power) but all same result.

Setting the pre-trigger to > 20% (was 1% & 10%) seems to fix the problem, trigger is stable at the first rise, I can capture both complete waveforms now with decoded 422 data.If only I could real time stamp the start of each decoded packet, that would be useful.